Our work will be directed towards confirming our observations that metaphase durations are prolonged in transformed cells and towards an understanding of mechanisms which regulate the duration of metaphase and thus the onset of chromosome movement. This work will include: 1) A study of metaphase durations in a variety of normal and transformed cells from several species, including epithelial and fibroblastic cells, carcinomas and sarcomas. 2.) We will do karyotype analyses of all lines to examine possible correlations between chromosome number and metaphase durations. 3) We will examine metaphase-to-prophase ratios to determine whether changes in this ratio correlate with alterations in metaphase durations and account for such changes in vivo. 4.) We will try to understand the mechanisms which regulate the duration of metaphase by studying the role of calcium and cyclic nucleotides in this process. Such studies will include the use of the ionophore A23187 and of cyclic nucleotide analogs. We will also include in this study an analysis of Chediak-Higashi cells.